What security feature does Envoy provide with mutual TLS?

Mutual TLS (Transport Layer Security) is a robust security feature that enhances the security of communications between services in Envoy. With mutual TLS, both the client and the server must present and validate their certificates during the handshake process. This two-way authentication ensures that not only does the client authenticate the server, but the server also verifies the identity of the client. As a result, this mechanism adds a strong layer of security by establishing trust in both directions, mitigating risks related to unauthorized access and impersonation.

In the context of the other options, although they represent important aspects of security, they do not correctly describe the unique feature provided by mutual TLS in Envoy. Encrypting outgoing traffic involves securing data in transit, which is a feature of TLS but does not specifically articulate the mutual aspect of authentication. Logging all authentication attempts and monitoring unauthorized access attempts can be part of a broader security framework but are not direct functions or benefits provided by mutual TLS itself. Thus, the emphasis on mutual authentication is what makes the correct answer stand out.